Federal contaminated sites long term monitoring: requirements

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According to the available FCSAP guidance materials, long-term monitoring may or may not be required depending on the nature and extent of remedial activities at a particular site. LTM is NOT typically required at sites that:

• have undergone remediation wherein all contaminated materials and media have been removed from the site and confirmatory sampling has been completed and confirms this;
• have had contaminated material or media treated such that no contaminants of concern have been left in place at concentrations above the remediation criteria established for the site and confirmatory sampling has been completed and confirms this;
• do not constitute a risk to human health or the environment and require no further remedial action based on the findings of a risk assessment; or
• have been investigated and demonstrated to not exceed applicable guidelines, standards or criteria, whether generic or risk-based.

Each site must also be evaluated for potential risk for migration of contaminants off the site and for ongoing impacts to the surrounding environment. 

R/RM at many federal contaminated sites, especially those that are remote, often involves leaving some contaminants on site. Risk management approaches that rely on containment, fixation or other sequestration methods to eliminate contaminant transport pathways to receptors generally require some level of ongoing monitoring. In the case of U.S. federal contaminated sites (Superfund sites) that rely on such methods, ongoing monitoring is required at five-year intervals in perpetuity.

The following are examples of remedial actions, infrastructure and situations that typically require LTM (US EPA, 2001):

• on-site waste encapsulation, stabilization or fixation;
• landfill caps or covers and slurry walls;
• site access controls such as roads, signage and fencing;
• sediment capping;
• sites at which R/RM has been implemented but where residual contaminants in soil, sediment or groundwater (usually at depth) are still present at levels above generic or site-specific criteria and represent a continuing threat to the receptors and potential users of the site; or
• sites where contaminants were left in place based on the results of a risk assessment (RA), but site conditions are dynamic and require confirmation that the site model on which the RA is based remains valid over time (e.g., submerged tailings or contaminated sediment or seasonal variation of water table).

A flowchart outlining the main remedial actions and criteria determining when LTM is required is provided in Figure 3.

Figure 3: Flowchart indicating when LTM may be required for a FCSAP site. CoCs = Contaminants of Concern; SCT = Site Closure Tool; TRAV = Tool for Risk Assessment Validation.

Consultation with custodian department representatives has indicated that other factors may be drivers for developing an LTM plan for a particular site. For instance, an LTM plan is a requirement for acquiring a water use licence from regulators in northern Canada such as the Nunavut Water Board. Such regulatory requirements are typical for many federal contaminated sites in northern Canada, especially mine and military sites. Legal/regulatory requirements for LTM are not usually very prescriptive and are generally performance-based -- for example, to prevent impacts to wildlife or fish habitat (Pike, 2011). Whether or not LTM is necessary for a particular RM strategy is a decision that must be made by the professional or group of professionals responsible for the site management.